Sex in the Grass

I was poking though old posts recently, spotted a minor typo in this one, thought, "what the heck," and corrected it.  That's when I made an important discovery: Blogger moved the post to the current date (from late June 2014 when originally posted), so that it went to the top of the blog.  Now I've learned my lesson, but will add this preamble and bump it once more, now that grasses are again coming into glorious flower

Okay: really "sex among the grasses" would have been more accurate--but would it have gotten your attention?

The grasses in my neighborhood are all hot-to-trot right about now, and that gives me the chance to talk about a pet peeve: the way people use the term "flower."  

A great many people are unaware of most flowering plants because they only notice flowers that are large and showy.  But showiness is just that: a bid to attract attention.  --just not ours.  

Showy flowers are in the business of attracting pollinators, to overcome one of the key disadvantages of the rooted life: an inability to go out dating.  For any sexual reproduction, sperm from the male must get to the egg of the female.  For most animals this is not a problem: they can move.  For plants it is a biggie.

Most plants overcome this problem by enclosing their sperm in a pollen grain, and then having some way to get this pollen grain from the male part (stamen) a longish distance to the female part (pistil) of the flower on another plant.  Most flowering plants do this with the help of animals recruited for the purpose.  These animal "chaperones"* are informed  of a plant's randy status with colors or odors, and  bribed with nectar or the like to be the go-between.  In a typically mutually beneficial arrangement, the animal (whether bee, bat, bird, etc) gets a reward for delivering the pollen to the receptive stigma of a flower on another plant, and then Baby is on the way.  Of course, it's helpful if you and your Honey are in the mood at the same time: hence flowering seasons.    More people should blush at the sight of blatant sex all around them.

Of course, the contented beetles are a good clue, but

how else can you tell that the swamp dogwood above is insect-pollinated, 

but the pignut hickory below is not?

Not all plants use animals as go-betweens.  Some prefer to let their love waft on the wind.  Among these are conifers, of course; the sperm-bearing pollen that pines coat all surfaces with at this time of year is the detritus of a veritable orgy.  But some flowering plants are also wind-pollinated: familiar oaks and maples release pollen from small, inconspicuous flowers with tiny, dull-colored petals because they have no need to attract animals.  One downside of this habit--at least for many of us--is seasonal allergies.  

 A few wind-pollinated trees: Norway maple, scarlet oak, and paper birch.

 

 The grasses go these trees one better: they don't even have petals.  For grasses, in particular, wind pollination makes sense: grasses typically live in in dense stands in which likely sexual partners are close by, so a little breeze is all that's required to complete the tryst. 

A few grasses from my neighborhood.

*In an old and jocular sense, and rather the opposite of what their parents intended.

Pine Pollen Week

Every summer pines everywhere dust everything with pollen.  Our white pines are prolific in this--among all the wind-pollinated trees, it is theirs that gets noticed by otherwise oblivious but fussy car owners, necessitating a visit to the carwash.  This year, attentive to phenology* as never before, I resolved to watch for the "flowering" of the pines. 

 May 14th

 May 23rd.  Each of the fat needle-like things is actually a bundle of five needles.

 May 27th

 

June 7th 

I waited in the spring while the white pines of the neighborhood lingered in the small, hard buds of winter.  In May I watched the buds soften, and in late May begin to lengthen into the "candles" that are a pine tree's way of growing new twigs and needles.  I watched for something to emerge from these twigs, among the five-fold bundles of needles that extended gradually from papery brown sheaths. The first clear evidence of pollen dusting surfaces came the first week in June.  On June 8 I finally spotted the little male cones in a mature tree.   

 Get your eye REAL close to the screen and squint.  (what I do, anyway.)

The little yellow things are clusters of male cones.

Only now did I scrutinized the pines in the knowledge that the male cones were there somewhere, and discover I had been looking in the wrong place: instead of the outsides and tops of the trees--easier to observe from the ground against the sky--the small male cones were crowded onto growing twigs lower down and more recessed, as if they shunned direct sunlight.  Though abundant, each golden cone was small as a child's little finger tip.  [I've since learned that the female cones are borne in the tree top, while the male are lower down: possibly to reduce the chance of falling pollen fertilizing female cones on the same tree.  (Nature usually frowns on self-fertilization, since it reinforces in the offspring harmful mutations.)]

 Pine pollen collected by dew on my kayak, 

and floated to the side of my rain barrel.

 Then, on June 11, came brief rain showers, and sidewalk puddles that evaporated to leave the tell-tale yellow shorelines of pollen.  I now walked the mile circumference of our "block" with one eye on the sidewalk and another looking for pines.  It struck me that the pollen seemed pretty evenly distributed--no one area more thickly coated than another--even though the trees were rather patchy.  Wind seems to be a pretty thorough, if random, dispersal agent. 

At that point, the pollen, so recently begun, seemed to be at an end: finding a tree that had male cones in reach, I took a twig, planning on taking a photo; but the cones crumbled before I could get the twig home.  A few days later the rain of fallen cones from one grand tree had formed thick shoals on the roadside. 

 This white pine--

 -- left this litter on the roadside (you can just make out pollen cones among the needles),

--in this quantity!

A few thoughts come to mind at this profligacy.  What an enormous expense a pine goes to to pass on its genes in its children--so inefficient compared to the targeting that comes with insect pollination.  And how critical that all the pines let go at once: just a week early or a week late, and all would be for naught: there would be no receptive female cones.  And should you be one of the few who are allergic to pine pollen, what of the sneezing you do for that week or so? it's pine sperm you're allergic to.  (Okay, not quite: the pollen itself isn't sperm, though each pollen grain delivers cargo of two sperm.)

*patterns of seasonal change in living things.